The Boundaries of the Cognitive Phenotype of Autism: Social Cognition and Central Coherence in Young People with Autistic Traits and their First Degree Relatives

Autism is a behaviourally defined disorder. The impairments in social communication and repetitive behaviours are individually non-specific. The disorder has indistinct boundaries both with other psychiatric disorders and with normal personality types. At the cognitive level, groups of people with autistic disorder can be differentiated from people without the disorder by their ability to reason about beliefs and knowledge (Theory of Mind) and by tests of visual disembedding (central coherence). This study examined whether young people with some of the behavioural features of autism but not necessarily a diagnosis, would show this distinctive cognitive profile. In a sample of 60 young people with additional learning support needs, we found that those with high levels of autistic traits (n=40) showed the same cognitive profile as has been found in people diagnosed with autistic disorder. This supports the view that autism is an extreme on a continuum of cognitive traits. Given the highly heritable nature of autism, we hypothesised that the parents of the young people with autistic traits will also display these cognitive features. The results indicated that there was no difference between the groups of parents on an advanced test of social cognition. Parents of people with high autistic traits were more resistant to one of the visual illusions and saw fewer reversals of an ambiguous figure when IQ was statistically controlled. These results in a sample with a low genetic load suggest ambiguous figures will be important in delineating the broader cognitive phenotype of autism.